1. Field of the Invention
This disclosure generally relates to automatic data collection (ADC) and more particularly to radio frequency identification (RFID).
2. Description of the Related Art
The ADC arts include a variety of data carrier types for automatically collecting and storing information. One such data carrier takes the form of an RFID tag, which is sometimes provided in the form of a card. Such RFID tags typically include an insert that is received in a label. The insert typically comprises at least one insulative substrate that carries one or more conductive patterns or traces that form an antenna on one side of the insulative substrate, and a semiconductor device including memory carried on the other side of the insulative substrate. The semiconductor device is electrically coupled to the antenna by electrical current paths formed as vias or throughholes in the insulative substrate. The label typically takes the form of an envelope or other structure for receiving the insert. The label may include a face sheet that may carry human-readable and/or machine-readable markings such as printing, and may include a pressure sensitive self-adhesive and release liner, for selectively exposing the pressure-sensitive self-adhesive for adhering the RFID tag to some article, object, and/or package.
RFID tags typically act as transponders, providing information stored in the semiconductor device in response to an RF signal, commonly referred to as an interrogation signal, received at the antenna from a reader or interrogator. Some RFID tags include security measures, such as passwords and/or encryption. Many RFID tags also permit information to be stored in the semiconductor memory via an RF signal. Some RFID tags, commonly referred to as active devices, include a discrete power source, for example, a battery. Other RFID tags, commonly referred to as passive devices, rely on an RF signal to drive power.
RFID tags advantageously do not require line-of-sight for reading and writing operations, in contrast to other data carriers such as machine-readable symbols (e.g., barcodes, area or matrix codes, stacked codes). This advantage, however, is offset by the relatively high cost of RFID tags when compared to other data carriers such as labels printed with machine-readable symbols. The cost difference is quite substantial, and is a predominant factor in the acceptance of RFID tags in the marketplace. Consequently, a low-cost RFID tag employing a minimal set of materials that is simple and cost-effective to manufacture is desirable.